Display device having an anisotropic scattering member

ABSTRACT

Disclosed herein is a display device including a reflection type image display portion having a sheet-like anisotropic scattering member. In an area, in an in-plane direction, of the anisotropic scattering member, a low-refractive index area and a high-refractive index area are disposed in a mixture style. The anisotropic scattering member is disposed in such a way that a light is scattered when an outside light is made incident from a surface side on which a degree of a change in a refractive index in a vicinity of a boundary between the low-refractive index area and the high-refractive index area is relatively large, and is emitted from a surface side on which the degree of the change in the refractive index in the vicinity of the boundary between the low-refractive index area and the high-refractive index area is relatively small.

CROSS REFERENCES TO RELATED APPLICATIONS

The present application claims priority to Japanese Priority PatentApplication JP 2012-049152 filed in the Japan Patent Office on Mar. 6,2012, the entire content of which is hereby incorporated by reference.

BACKGROUND

The present disclosure relates to a display device. More particularly,the present disclosure relates to a display device including an imagedisplay portion using a sheet-like anisotropic scattering member.

A reflection type image display portion is known which displays thereonan image by controlling a reflectivity of an outside light. For example,a reflection type liquid crystal display panel includes a reflectiveelectrode which reflects an outside light. Thus, the reflection typeliquid crystal display panel displays thereon an image by controllingthe reflectivity of the outside light through a liquid crystal materiallayer. Since a display device including the reflection type imagedisplay portion displays thereon an image by utilizing the outsidelight, it is possible to attain the low power consumption, the thinning,and the weight saving. For this reason, the display device including thereflection type image display portion, for example, is utilized for amobile terminal.

In the display device including the reflection type image displayportion, scattering characteristics of the light in a display area ofthe image display portion are given an angle dependency, whereby areflectivity for a predetermined observation position is increased,thereby making it possible to compensate for visibility reduction due toreflectivity reduction following the color displaying. In addition, animage can be prevented from being observed from a place out of thepredetermined observation position. An anisotropic scattering member,which is used for view angle control or the like for the display device,and in which areas different in refractive index from one another aredisposed in a mixture style, for example, is described in JapanesePatent Laid-Open Nos. 2000-297110 and 2008-239757.

SUMMARY

However, in the display device using the anisotropic scattering memberhaving the structure described above, due to the interference of thelights owing to the fine structure of the anisotropic scattering member,the rainbow-coloring or the like is generated to impair the visualquality in some cases.

The present disclosure has been made in order to solve the problemdescribed above, and it is therefore desirable to provide a displaydevice in which rainbow-coloring due to a structure of an anisotropicscattering member can be reduced.

According to an embodiment of the present disclosure, there is provideda display device including a reflection type image display portionhaving a sheet-like anisotropic scattering member. In an area, in anin-plane direction, of the anisotropic scattering member, alow-refractive index area and a high-refractive index area are disposedin a mixture style. The anisotropic scattering member is disposed insuch a way that a light is scattered when an outside light is madeincident from a surface side on which a degree of a change in arefractive index in a vicinity of a boundary between the low-refractiveindex area and the high-refractive index area is relatively large, andis emitted from a surface side on which the degree of the change in therefractive index in the vicinity of the boundary between thelow-refractive index area and the high-refractive index area isrelatively small.

According to the embodiments of the present disclosure, the anisotropicscattering member is disposed in such a way that the light is scatteredwhen the light is made incident from the surface side on which thedegree of the change in the refractive index in the vicinity of theboundary between the low-refractive index area and the high-refractiveindex area is relatively large, and is emitted from the surface side onwhich the degree of the change in the refractive index in the vicinityof the boundary between the low-refractive index area and thehigh-refractive index area is relatively small. As a result, it ispossible to lighten the rainbow-coloring due to the interference of thelights owing to the fine structure of the anisotropic scattering member.

Additional features and advantages are described herein, and will beapparent from the following Detailed Description and the figures.

BRIEF DESCRIPTION OF THE FIGURES

FIG. 1 is a schematic perspective view showing a display deviceaccording to a first embodiment of the present disclosure;

FIGS. 2A, 2B, 2C, and 2D are respectively a schematic perspective viewexplaining a construction of a reflection type image display portionaccording to the first embodiment, a schematic cross sectional viewexplaining a structure of an anisotropic scattering member according tothe first embodiment, and schematic perspective views each explaining adisposition of a low-refractive index area and a high-refractive indexarea in the anisotropic scattering member;

FIGS. 3A and 3B are schematic views explaining a method of manufacturingthe anisotropic scattering member according to the first embodiment;

FIGS. 4A and 4B are schematic views each explaining a relationshipbetween an incident light and a scattered light in the anisotropicscattering member;

FIG. 5 is a schematic view explaining a positional relationship betweenthe display device and an image observer when outside lights which areapproximately parallel with one another are made incident;

FIGS. 6A and 6B are respectively a schematic cross sectional view of thereflection type image display portion according to the first embodiment,and a schematic cross sectional view of a reflection type image displayportion according to a reference example;

FIGS. 7A and 7B are respectively a schematic cross sectional view of areflection type image display portion according to a second embodimentof the present disclosure, and a schematic cross sectional view of areflection type image display portion according to a reference example;

FIG. 8 is a schematically exploded perspective view showing a reflectiontype image display portion according to a third embodiment of thepresent disclosure;

FIG. 9 is a schematically exploded perspective view showing a reflectiontype image display portion according to a fourth embodiment of thepresent disclosure; and

FIG. 10 is a schematic cross sectional view showing the reflection typeimage display portion according to the fourth embodiment of the presentdisclosure.

DETAILED DESCRIPTION

Embodiments of the present disclosure will be described in detailhereinafter with reference to the accompanying drawings. The presentdisclosure is by no means limited to the embodiments, and various kindsof numerical values and materials in the embodiments are merelyexemplified. In the following description, the same constituent elementsor constituent elements having the same functions are designated by thesame reference numerals or symbols, and a repeated description thereofis omitted for the sake of simplicity. It is noted that the descriptionwill be given below in accordance with the following order.

1. Description of Display Device and the Whole thereof of the PresentDisclosure

2. First Embodiment

3. Second Embodiment

4. Third Embodiment

5. Fourth Embodiment

1. Description of Display Device and the Whole Thereof of the PresentDisclosure

In a display device according to the embodiments of the presentdisclosure, it is possible to adopt a structure in which an anisotropicscattering member is disposed in such a way that a light is scatteredwhen an outside light reflected within an image display portion istransmitted through the anisotropic scattering member. Or, it is alsopossible to adopt a structure in which the anisotropic scattering memberis disposed in such a way that a light is scattered when an outsidelight made incident from the outside is transmitted through theanisotropic scattering member.

The anisotropic scattering member can include a composition containingtherein a photoreactive compound or the like. For example, a light suchas an ultraviolet light is radiated from a predetermined direction to abase material having a composition exhibiting a certain amount ofrefractive index change before and after photopolymerization, therebymaking it possible to obtain the anisotropic scattering member. As faras a material composing the composition, it is only necessary that amaterial in which a certain amount of refractive index change isgenerated between a portion photoreacted and a portion not photoreactedis suitably selected from known photoreactive materials such as polymerhaving a radical-polymerizable or cationic-polymerizable functionalgroup to use the photoreactive material thus selected.

Or, for example, a light such as an ultraviolet light is radiated from apredetermined direction to a base material having a composition in whicha photoreactive compound and a non-photoreactive high-molecular compoundare mixed with each other, thereby making it possible to obtain theanisotropic scattering member. It is only necessary that thenon-photoreactive high-molecular compound, for example, is suitablyselected from known materials such as an acrylic resin and a styreneresin to use the material thus selected.

A composition, for example, is applied onto a film-like base materialhaving a high-molecular material by utilizing a known application methodor the like, thereby making it possible to obtain the base materialhaving the composition described above.

In an area, in an in-plane direction, of the anisotropic scatteringmember having the composition or the like described above, alow-refractive index area and a high-refractive index area are disposedin a mixture style. A boundary between the low-refractive index area andthe high-refractive index area make a predetermined angle with athickness direction of the anisotropic scattering member. Thispredetermined angle may continuously change in the in-plane direction asthe case may be.

Qualitatively, when the light is radiated to the base material havingthe composition, the photoreaction of the composition proceeds in aportion of the base material closer to the light radiation side.Therefore, in a surface to which the light is radiated, the degree ofthe change in the refractive index in the vicinity of the boundarybetween the low-refractive index area and the high-refractive index areabecomes relatively large. In a surface opposite to that surface, thedegree of the change in the refractive index in the vicinity of theboundary between the low-refractive index area and the high-refractiveindex area becomes relatively small.

A difference in refractive index between the low-refractive index areaand the high-refractive index area is normally preferably 0.01 or morein the vicinity of the surface in which the degree of the change in therefractive index in the vicinity of the boundary between thelow-refractive index area and the high-refractive index area isrelatively large, more preferably 0.05 or more, and is further morepreferably 0.10 or more.

Although depending on the material composing the anisotropic scatteringmember and on a method of manufacturing the anisotropic scatteringmember, the portion photoreacted and the portion not photoreacted, forexample, may form louver-like areas, respectively, as shown in FIG. 2Cwhich will be described later. Or, the portion photoreacted and theportion not photoreacted may form a columnar area and a peripheral areasurrounding the columnar area as shown in FIG. 2D which will bedescribed later.

A reflection type image display portion composing the display deviceaccording to the embodiments of the present disclosure, for example, caninclude a reflection type liquid crystal display panel. The imagedisplay portion may be adapted either to monochrome display or to colordisplay. The reflection type liquid crystal display panel includes areflective electrode which reflects the outside light, and displaysthereon an image by controlling reflectivity of the outside light by aliquid crystal material layer.

The reflection type liquid crystal display panel, for example, includesa front substrate including a transparent common electrode, a backsubstrate including a pixel electrode, the liquid crystal material layerdisposed between the front substrate and the back substrate, and thelike. The pixel electrode itself may be structured as a reflectiveelectrode so as to reflect a light. Or, a reflective film may reflect alight by a combination of the transparent pixel electrode and thereflective film. An operation mode of the liquid crystal display panelis not especially limited as long as a reflection type display operationis left untouched. For example, it is possible to use a liquid crystaldisplay panel which is driven in a so-called Vertical Alignment (VA)mode or Electronic CodeBook (ECB) mode.

In the display device of the embodiments of the present disclosureincluding the various kinds of preferable structures described above,the image display portion may have the reflection type liquid crystaldisplay panel including the front substrate, the back substrate, and theliquid crystal material layer disposed between the front substrate andthe back substrate. The anisotropic scattering member may be disposed onthe front substrate side.

In the display device of the embodiments of the present disclosureincluding the various kinds of preferable structures described above,the anisotropic scattering member may have plural scattering membersdifferent in scattering characteristics from one another laminated oneupon another.

A semi-transmission type liquid crystal display panel which, forexample, has both of a reflection type display area and a transmissiontype display area within a pixel is known as a semi-transmission typeimage display portion having both of reflection type characteristics andtransmission type characteristics. Such a semi-transmission type imagedisplay portion may also be adopted as the case may be. That is to say,“the semi-transmission type image display portion” is also included in“the reflection type image display portion.”

A shape of the image display portion is not especially limited, and thusmay be either a horizontally long rectangular shape or a vertically longrectangular shape. When the number (M×N) of pixels in the image displayportion is represented as (M, N), for example, in the case of thehorizontally long rectangular shape, several resolutions for the imagedisplay such as (640, 480), (800, 600), and (1024, 768) can beexemplified as a value of (M, N). In the case of the vertically longrectangular shape, the resolutions in which the values in the case ofthe horizontally long rectangular shape are replaced with each otherwith respect to M and N can be exemplified. However, the presentdisclosure is by no means limited to these values.

A driving circuit adapted to drive the pixel display portion can includevarious kinds of circuits. Well-known circuit elements or the like maybe used for the various kinds of circuits.

The various kinds of conditions shown in this specification arefulfilled in a case as well where they substantially hold in addition toa case where they strictly hold. The presence of various kinds ofdispersions generated in the design or in the manufacture is allowed.

2. First Embodiment

A first embodiment relates to the display device according to thepresent disclosure.

FIG. 1 is a schematic perspective view showing a display deviceaccording to a first embodiment of the present disclosure.

As shown in FIG. 1, a display device 100 includes a reflection typeimage display portion 1 having a display area 11 in which pixels 12 aredisposed. The image display portion 1 includes a reflection type liquidcrystal display panel and is incorporated in a chassis 40. The imagedisplay portion 1 is driven by a driving circuit (not shown) and thelike. It is noted that in FIG. 1, the display device 100 is shown in astate in which part of the chassis 40 is broken away. An outside lightsuch as a solar light is made incident to the display area 11. For theconvenience of the description, it is supposed that the display area 11is parallel with an X-Y plane, and an image observation side is in a +Zdirection.

FIG. 2A is a schematic perspective view explaining a construction of thereflection type image display portion. FIG. 2B is a schematic crosssectional view explaining a structure of an anisotropic scatteringmember according to the first embodiment. FIGS. 2C and 2D are schematicperspective views each explaining a disposition of a low-refractiveindex area and a high-refractive index area in the anisotropicscattering member.

The image display portion 1 shown in FIG. 2A is a reflection type imagedisplay portion including a sheet-like anisotropic scattering member 20.More specifically, the image display portion 1 has a reflection typeliquid crystal display panel including a front substrate, a backsubstrate, and a liquid crystal material layer disposed between thefront substrate and the back substrate. Reference numeral 10 shown inFIG. 2A designates a portion of the liquid crystal display panelincluding a front substrate 18, a back substrate 14, and a liquidcrystal material layer 17 disposed between the front substrate 18 andthe back substrate 14 which are all shown in FIG. 6A which will bedescribed later. The anisotropic scattering member 20 is disposed on thefront substrate 18 side. Reference numeral 30 shown in FIG. 2Adesignates a portion of the liquid crystal display panel including aquarter-wave plate 31, a half-wave plate 32, and a polarizing plate 33which are all shown in FIG. 6A.

As shown in FIG. 2A, the image display portion 1 has a rectangularshape, and four sides thereof are designated by reference symbols 13A,13B, 13C, and 13D, respectively. The side 13C is a side on the nearside, and the side 13A is a side facing the side 13C. For example, thelength of each of the sides 13A and 13C is about 12 cm, and the lengthof each of the sides 13B and 13D is about 16 cm. These values are merelyexemplified.

The anisotropic scattering member 20, for example, has a sheet-like(film-like) shape having a thickness of about 0.02 to 0.5 mm. In anarea, in an in-plane direction, of the anisotropic scattering member 20,a low-refractive index area 21 and a high-refractive index area 22, forexample, are disposed in a mixture style on the micron order. It isnoted that, for convenience of an illustration in FIGS. 2A to 2D and thelike, an illustration of a transparent film or the like becoming a baseof the anisotropic scattering member 20 is omitted here.

Although a detailed description will be given later with reference toFIG. 6A and the like which will be described later, the anisotropicscattering member 20 is disposed in such a way that the light isscattered when the outside light is made incident from the surface sideon which the degree of the change in the refractive index in thevicinity of the boundary between the low-refractive index area 21 andthe high-refractive index area 22 is relatively large, and is emittedfrom the surface side on which the degree of the change in therefractive index in the vicinity of the boundary between thelow-refractive index area 21 and the high-refractive index area 22 isrelatively small. In the first embodiment of the present disclosure, theanisotropic scattering member 20 is disposed in such a way that thelight is scattered when the outside light reflected within the imagedisplay portion 1 is transmitted through the anisotropic scatteringmember 20.

The anisotropic scattering member 20 includes a composition containingtherein a photoreactive compound. The anisotropic scattering member 20,for example, as shown in FIG. 2C, may have the low-refractive index area21 and the high-refractive index area 22 formed in a louver-like shape.Or, as shown in FIG. 2D, the anisotropic scattering member 20 may havethe low-refractive index area 21 and the high-refractive index area 22forming a columnar area and a peripheral area surrounding the columnararea. In the case of FIG. 2D, for example, there is shown a case where aportion of the photoreacted composition exhibits the increasedrefractive index in the columnar area shape.

Although in FIG. 2C, a width, in a thickness direction, of each oflow-refractive index areas 21 and a width, in the thickness direction,of each of high-refractive index areas 22 are represented so as to beconstant, this is merely exemplified. Likewise, although in FIG. 2D aswell, the shapes of columnar areas are represented so as to be identicalto one another, this is also merely exemplified.

As shown in FIGS. 2B to 2D, the low-refractive index area 21 and thehigh-refractive index area 22 are formed obliquely inside theanisotropic scattering member 20 in such a way that the boundary betweenthe low-refractive index area 21 and the high-refractive index area 22makes an angle θ with the thickness direction of the anisotropicscattering member 20 (the Z-axis direction). The angle θ is suitably setto a preferable value in accordance with the specification and the likeof the anisotropic scattering member 20. The angle θ may be zero as thecase may be.

As shown in FIGS. 4A and 4B which will be described later, a scatteringcentral axis S of the anisotropic scattering member 20 (The scatteringcentral axis S is an axis with respect to which the anisotropicscattering characteristics of the incident light become approximatelysymmetry. In a word, it is an axis extending in an incidence directionof a most scattered light) is inclined obliquely with respect to anormal line direction (the Z-axis direction) to an observation surfaceof the display device 100. Qualitatively, however, the direction of thescattering central axis S is thought to be aligned with a directionapproximately following an extension direction of the low-refractiveindex area 21 and the high-refractive index area 22. In addition, inthis case, an azimuth direction obtained by projecting the scatteringcentral axis S on the X-Y plane, in the case shown in FIG. 2C, isthought to be aligned with a direction perpendicular to an extensiondirection of the louver-like areas. In the case shown in FIG. 2D, theazimuth direction obtained by projecting the scattering central axis Son the X-Y plane is thought to be aligned with a direction in which ashadow extends when the columnar area is projected on the X-Y plane.

For the convenience of the description, in this case, it is supposedthat the low-refractive index areas 21 and the high-refractive indexareas 22, as shown in FIG. 2C, are formed in the louver-like shape, andthat the direction in which these louver-like areas extend is inparallel with the X-axis direction. Although the high-refractive indexarea 22 is described as the area in which the base material causes thephotoreaction, this is merely exemplified. Alternatively, the area inwhich the base material causes the photoreaction may be thelow-refractive index area 21.

A method of manufacturing the anisotropic scattering member 20 will nowbe described with reference to FIGS. 3A and 3B. As shown in FIG. 3A, forexample, a light is obliquely radiated from a light radiating device 50to a base material 20′ obtained by applying a photoreactive compositiononto a base such as a PET film through a mask 60 having openings 61formed therein, thereby making it possible to manufacture theanisotropic scattering member 20. It is noted that the light may beradiated with the mask 60 being omitted as the case may be. Of surfacesof the base materials 20′, a surface on a side to which the light isradiated from the light radiating device 50 is represented as a surfaceA, and a surface opposite to the surface A is represented as a surfaceB.

Qualitatively, the photoreaction of the composition proceeds in an areacloser to the light radiating side due to the influence of thediffraction of the light, the light absorption by the composition or thelike. Therefore, as shown in FIG. 3B, the surface A to which the lightis radiated becomes a surface in which the degree of the change in therefractive index in the vicinity of the boundary between thelow-refractive index area 21 and the high-refractive index area 22 isrelatively large. The surface B on the opposite side becomes a surfacein which the degree of the change in the refractive index in thevicinity of the boundary between the low-refractive index area 21 andthe high-refractive index area 22 is relatively small.

Here, a difference between the case where the outside light is madeincident from the surface A side of the anisotropic scattering member20, and the case where the outside light is made incident from thesurface B side of the anisotropic scattering member 20 will be describedwith reference to FIGS. 4A and 4B.

As shown in FIGS. 4A and 4B, in the anisotropic scattering member 20,when the light is made incident from the direction approximatelyfollowing the direction in which the boundary between the low-refractiveindex area 21 and the high-refractive index area 22 extends, the lightis scattered to be emitted. When the light is made incident from thedirection approximately perpendicular to the direction in which theboundary between the low-refractive index area 21 and thehigh-refractive index area 22 extends, the light is transmitted as itis.

As shown in FIG. 4A, in the case where the light is scattered when thelight is made incident from the surface B side to be emitted from thesurface A side, the scattered lights are emitted from the surface inwhich the degree of the change in the refractive index in the vicinityof the boundary between the low-refractive index area 21 and thehigh-refractive index area 22 is relatively large. As a result,rainbow-coloring due to the interference of the lights owing to the finestructure of the anisotropic scattering member 20 is conspicuous.

As shown in FIG. 4B, in a case where the light is scattered when thelight is made incident from the surface A side to be emitted from thesurface B side, the scattered lights are emitted from the surface inwhich the degree of the change in the refractive index in the vicinityof the boundary between the low-refractive index area 21 and thehigh-refractive index area 22 is relatively small. As a result, therainbow-coloring due to the interference of the lights owing to the finestructure of the anisotropic scattering member 20 is reduced.

FIG. 5 is a schematic view explaining a positional relationship betweenthe display device and an image observer when outside lightsapproximately parallel with one another are made incident. Specifically,FIG. 5 shows a state when the image observer observes an image in aplace which is located at a distance LZ from the display area 11 in astate in which the incidence direction of the outside lights and thenormal line direction to the image display portion 1 are caused to makean angle α with each other.

A behavior of the light in the image display portion 1 at this time willbe described with reference to FIG. 6A.

A planarizing film 15 made of a high-molecular material such as acrylicresin is formed on the back substrate 14, for example, made of a glassmaterial. A reflective electrode (pixel electrode) 16 made of a metallicmaterial such as aluminum is formed on the planarizing film 15. Thereflective electrode 16 is formed in a mirror-like shape in a surfacethereof, and is provided so as to correspond to each of the pixels 12.For the purpose of controlling the electrical connection between asignal line and the reflective electrode 16, elements such as Thin FilmTransistors (TFTs) are connected so as to correspond to the pixels 12,respectively. It is noted that in FIGS. 3A and 3B, an illustration ofthe TFTs and various kinds of wirings such as the signal line is omittedfor the sake of simplicity.

A common electrode (not shown) made of a transparent conductive materialsuch as Indium Tin Oxide (ITO) is provided on the front substrate 18,for example, made of a glass material. In the case of the color display,the pixel 12 includes a pair of sub-pixels. A color filter and the likeare provided so as to correspond to the sub-pixels, respectively. It isnoted that for convenience of the illustration, in FIGS. 6A and 6B, andthe like, an illustration of the common electrode and the like isomitted.

The liquid crystal material layer 17 is disposed between the frontsubstrate 18 and the back substrate 14. Reference symbol 17Aschematically designates a liquid crystal molecule composing the liquidcrystal material layer 17. The liquid crystal material layer 17 isinstalled in such a thickness that, when the light travels back andforth through the liquid crystal material layer 17, the liquid crystalmaterial layer 17 operates as a half-wave plate under a predeterminedcondition through a spacer (not shown) or the like.

The anisotropic scattering member 20 is disposed on the surface on theside opposite to the liquid crystal material layer 17 side of the frontsubstrate 18. The quarter-wave plate 31, the half-wave plate 32, and thepolarizing plate 33 are disposed on the anisotropic scattering member 20in this order.

After the outside light made incident from the outside has become alinearly polarized light in a predetermined direction through thepolarizing plate 33, the outside light is then transmitted through bothof the half-wave plate 32 and the quarter-wave plate 31 to become acircularly polarized light. A combination of the half-wave plate 32 andthe quarter-wave plate 31 operates as a broad-band quarter-wave plate.The outside light which has become the circularly polarized light ismade incident from the direction approximately perpendicular to thedirection in which the boundary between the low-refractive index area 21and the high-refractive index area 22 extends. Thus, after the outsidelight has been transmitted through the anisotropic scattering member 20as it is, the outside light is transmitted through the liquid crystalmaterial layer 17 and is then reflected by the reflective electrode 16.The outside light thus reflected is transmitted through the liquidcrystal material layer 17 and is then made incident from the surface Aside of the anisotropic scattering member 20 to be emitted from thesurface B side. The light is scattered because the light is madeincident from the direction approximately following the direction inwhich the boundary between the low-refractive index area 21 and thehigh-refractive index area 22 extends. However, since the light isemitted from the surface in which the degree of the change in therefractive index in the vicinity of the boundary between thelow-refractive index area 21 and the high-refractive index area 22 isrelatively small, the rainbow-coloring due to the interference of thelights owing to the fine structure of the anisotropic scattering member20 is reduced. After that, the light thus scattered is transmittedthrough both of the quarter-wave plate 31 and the half-wave plate 32 toreach the polarizing plate 33, and is then emitted toward the outside.An orientational state of liquid crystal molecules 17A in the liquidcrystal material layer 17 is controlled by controlling a voltage to beapplied to the reflective electrode 16 or the like, whereby it ispossible to control an amount of outside light which is reflected by thereflective electrode 16 and is then transmitted through the polarizingplate 33.

A description will now be given with respect to a behavior of the lightwhen the surface A side and the surface B side of the anisotropicscattering member 20 are replaced with each other. The behavior of thelight in an image display portion 1′ in a reference example in which thesurface A side and the surface B side of the anisotropic scatteringmember 20 are replaced with each other will now be described withreference to FIG. 6B.

In this case, the behavior until the outside light reflected by thereflective electrode 16 is transmitted through the liquid crystalmaterial layer 17 is the same as that described above. The reflectedoutside light is transmitted through the liquid crystal material layer17 and is then made incident from the surface B side of the anisotropicscattering member 20 to be emitted from the surface A side. The light isscattered because the light is made incident from the directionapproximately following the direction in which the boundary between thelow-refractive index area 21 and the high-refractive index area 22extends. Since the light is emitted from the surface in which the degreeof the change in the refractive index in the vicinity of the boundarybetween the low-refractive index area 21 and the high-refractive indexarea 22 is relatively large, the rainbow-coloring due to theinterference of the lights owing to the fine structure of theanisotropic scattering member 20 is conspicuous.

In such a manner, in the first embodiment of the present disclosure, theanisotropic scattering member is disposed in such a way that the lightis scattered when the outside light is made incident from the surfaceside on which the degree of the change in the refractive index in thevicinity of the boundary between the low-refractive index area and thehigh-refractive index area is relatively large, and is emitted from thesurface side on which the degree of the change in the refractive indexin the vicinity of the boundary between the low-refractive index areaand the high-refractive index area is relatively small. Morespecifically, the anisotropic scattering member is disposed in such away that the light is scattered when the outside light reflected withinthe image display portion is transmitted through the anisotropicscattering member to travel toward the outside. The light is scatteredwhen the light is emitted from the surface in which the degree of thechange in the refractive index in the vicinity of the boundary betweenthe low-refractive index area and the high-refractive index area isrelatively small. As a result, rainbow-coloring due to the interferenceof the lights owing to the fine structure of the anisotropic scatteringmember is reduced.

3. Second Embodiment

A second embodiment also relates to the display device according to thepresent disclosure.

The second embodiment is different from the first embodiment in that theanisotropic scattering member is disposed in such a way that the lightis scattered when the outside light made incident from the outside istransmitted through the anisotropic scattering member.

A display device 200 of the second embodiment has the same structure asthat of the display device 100 of the first embodiment except that thedisposition of the anisotropic scattering member in the secondembodiment is different from that of the anisotropic scattering memberin the first embodiment. A schematic perspective view of the displaydevice 200 of the second embodiment is omitted here because it is onlynecessary that the image display portion 1 shown in FIG. 1 is replacedwith an image display portion 2, and the display device 100 is replacedwith the display device 200. A schematic perspective view explaining astructure of the image display portion 2 used in the second embodimentis omitted here because it is only necessary that the disposition of theanisotropic scattering member 20 shown in FIG. 2A is replaced withanother one by carrying out suitable change, and the image displayportion 1 is replaced with the image display portion 2.

In the second embodiment as well, the anisotropic scattering member 20is disposed in such a way that the light is scattered when the outsidelight is made incident from the surface side on which the degree of thechange in the refractive index in the vicinity of the boundary betweenthe low-refractive index area 21 and the high-refractive index area 22is relatively large, and is emitted from the surface side on which thedegree of the change in the refractive index in the vicinity of theboundary between the low-refractive index area 21 and thehigh-refractive index area 22 is relatively small. In the secondembodiment of the present disclosure, the anisotropic scattering member20 is disposed in such a way that the light is scattered when theoutside light made incident from the outside is transmitted through theanisotropic scattering member 20.

A behavior of the light in the image display portion 2 in a state inwhich the incidence direction of the outside light and the normal linedirection to the image display portion 2 are caused to make an angle αwith each other similarly to the description given in the firstembodiment will now be described with reference to FIG. 7A.

As shown in FIG. 7A, after the outside light made incident from theoutside has been transmitted through the polarizing plate 33, thehalf-wave plate 32, and the quarter-wave plate 31, the outside light ismade incident to the anisotropic scattering member 20. Unlike the firstembodiment, the anisotropic scattering member 20 is disposed in such away that the direction in which the boundary between the low-refractiveindex area 21 and the high-refractive index area 22 extendsapproximately follows the direction of the incident light. The outsidelight is scattered when the outside light is made incident from thesurface A side and is then emitted from the surface B side. The light isscattered when the light is emitted from the surface in which the degreeof the change in the refractive index in the vicinity of the boundarybetween the low-refractive index area 21 and the high-refractive indexarea 22 is relatively small. As a result, the rainbow-coloring due tothe interference of the lights owing to the fine structure of theanisotropic scattering member 20 is reduced. The light thus scattered istransmitted through the liquid crystal material layer 17 and is thenreflected by the reflective electrode 16 to be transmitted through theliquid crystal material layer 17. Then, the light is made incident fromthe surface B side of the anisotropic scattering member 20 to be emittedfrom the surface A side of the anisotropic scattering member 20. Thelight is made incident from the direction approximately perpendicular tothe direction in which the boundary between the low-refractive indexarea 21 and the high-refractive index area 22 extends. Therefore, thelight is transmitted through the anisotropic scattering member 20 as itis, and is then transmitted through both of the quarter-wave plate 31and the half-wave plate 32 to reach the polarizing plate 33, and is thenemitted toward the outside.

A description will now be given with respect to a behavior of the lightwhen the surface A side and the surface B side of the anisotropicscattering member 20 are replaced with each other. The behavior of thelight in an image display portion 2′ of a reference example in which thesurface A side and the surface B side of the anisotropic scatteringmember 20 are replaced with each other will now be described withreference to FIG. 7B.

In this case, the outside light made incident from the outside isscattered when the outside light is emitted from the surface in whichthe degree of the change in the refractive index in the vicinity of theboundary between the low-refractive index area 21 and thehigh-refractive index area 22 is relatively large. Therefore, therainbow-coloring due to the interference of the lights owing to the finestructure of the anisotropic scattering member 20 is conspicuous. Thebehavior until the scattered light is reflected by the reflectiveelectrode 16 to travel toward the outside is the same as that describedabove.

As described above, in the second embodiment, the anisotropic scatteringmember is disposed in such a way that the light is scattered when theoutside light made incident from the outside is transmitted through theanisotropic scattering member. The light is scattered when the light isemitted from the surface in which the degree of the change in therefractive index in the vicinity of the boundary between thelow-refractive index area and the high-refractive index area isrelatively small. As a result, the rainbow-coloring due to theinterference of the lights owing to the fine structure the anisotropicscattering member is reduced.

4. Third Embodiment

A third embodiment also relates to the display device according to thepresent disclosure.

The third embodiment is different from the first embodiment in that theanisotropic scattering member includes plural scattering members,different in scattering characteristics from one another, laminated oneupon another.

A display device 300 according to the third embodiment of the presentdisclosure has the same structure as that of the display device 100according to the first embodiment of the present disclosure except thatthe structure of the anisotropic scattering member in the thirdembodiment is different from that of the anisotropic scattering memberin the first embodiment. A schematic perspective view of the displaydevice 300 of the third embodiment is omitted here because it is onlynecessary that the image display portion 1 shown in FIG. 1 is replacedwith an image display portion 3, and the display device 100 is replacedwith the display device 300. A schematic perspective view explaining astructure of the image display portion 3 used in the third embodiment isomitted here because it is only necessary that the anisotropicscattering member 20 shown in FIG. 2A is replaced with another one bycarrying out suitable change, and the image display portion 1 isreplaced with the image display portion 3.

FIG. 8 is a schematic exploded perspective view showing the reflectiontype image display portion according to the third embodiment.

As shown in FIG. 8, in the image display portion 3, a scattering member20A and a scattering member 20B are laminated on top of each other. Astructure and a disposition of the scattering member 20A are the same asthose of the anisotropic scattering member 20 previously described inthe first embodiment.

A structure of the scattering member 20B is also the same as that of theanisotropic scattering member 20 previously described in the firstembodiment. However, in the image display portion 3, the scatteringmember 20B is disposed in such a way that a direction in which itslouver-like structure is inclined is perpendicular to a direction inwhich the louver-like structure is inclined in the scattering member20A.

A direction of the scattering central axis S of the scattering member20A is different from that of the scattering member 20B. Also, a shapeof an area in which the light diffuses of the scattering member 20A isdifferent from that of the scattering member 20B. Therefore, pluralscattering members different in the scattering characteristics from oneanother are laminated one upon another, thereby structuring ananisotropic scattering member 320.

In such a way, the plural scattering members different in the scatteringcharacteristics from one another are laminated one upon another, therebymaking it possible to adjust a diffusion range of the light.

For example, if in the scattering member 20A, the area in which thelight diffuses has an elliptical shape with a Y-axis as a long axis, inthe scattering member 20B, the area in which the light diffuses becomesan elliptical shape with an X-axis as a long axis. Therefore, when thescattering members 20A and 20B are laminated on top of each other, thearea in which the light diffuses becomes approximately a square andround shape. Therefore, even if a line of sight moves in some degree ofwidth in the vertical and horizontal directions, it is possible toobserve an excellent image.

5. Fourth Embodiment

A fourth embodiment also relates to the display device according to thepresent disclosure.

The fourth embodiment is also different from the first embodiment inthat the anisotropic scattering member includes plural scatteringmembers, different in scattering characteristics from one another,laminated one upon another.

The display device 400 according to the fourth embodiment of the presentdisclosure has the same structure as that of the display device 100according to the first embodiment of the present disclosure except thatthe structure of the anisotropic scattering member in the fourthembodiment is different from that of the anisotropic scattering memberin the first embodiment. A schematic perspective view of the displaydevice 400 of the fourth embodiment is omitted here because it is onlynecessary that the image display portion 1 shown in FIG. 1 is replacedwith an image display portion 4, and the display device 100 is replacedwith the display device 400. A schematic perspective view explaining astructure of the image display portion 4 used in the fourth embodimentis omitted here because it is only necessary that the anisotropicscattering member 20 shown in FIG. 2A is replaced with another one bycarrying out suitable change, and the image display portion 1 isreplaced with the image display portion 4.

FIG. 9 is a schematic exploded perspective view showing the reflectiontype image display portion according to the fourth embodiment.

As shown in FIG. 9, in the image display portion 4, the scatteringmember 20A and a scattering member 20C are laminated on top of eachother. The structure and disposition of the scattering member 20A arethe same as those of the anisotropic scattering member 20 previouslydescribed in the first embodiment.

The scattering member 20C has the same structure as that of theanisotropic scattering member 20 previously described in the firstembodiment except that the value of the angle θ shown in FIG. 2B isdifferent. In the image display portion 4, the disposition is carriedout in such a way that a direction in which the louver-like structure isinclined in the scattering member 20C follows the direction in which thelouver-like structure is inclined in the scattering member 20A.

FIG. 10 is a schematic cross sectional view showing the reflection typeimage display portion according to the fourth embodiment of the presentdisclosure.

A direction of the scattering central axis S of the scattering member20A is different from that of the scattering member 20C. Also, the shapeof the area in which the light diffuses of the scattering member 20A isdifferent from that of the scattering member 20C. Therefore, pluralscattering members different in the scattering characteristics from oneanother are laminated one upon another, thereby structuring ananisotropic scattering member 420. In such a way, the plural scatteringmembers different in the scattering characteristics from one another arelaminated one upon another, thereby making it possible to adjust thediffusion range of the light.

Although the present disclosure has been concretely described so farbased on the embodiments, the present disclosure is by no means limitedto the embodiments described above, and various kinds of changes thereofbased on the technical idea of the present disclosure can be made.

For example, although in each of the first to fourth embodiments, theanisotropic scattering member is disposed between the front substrate 18and the quarter-wave plate 31, this structure is merely exemplified. Itis only necessary that the place where the anisotropic scattering memberis disposed is suitably determined in accordance with the design andspecification of the display device.

It is noted that the present disclosure can also adopt followingconfigurations.

(1) A display device including:

a reflection type image display portion having a sheet-like anisotropicscattering member,

in which in an area, in an in-plane direction, of the anisotropicscattering member, a low-refractive index area and a high-refractiveindex area are disposed in a mixture style, and

the anisotropic scattering member is disposed in such a way that a lightis scattered when an outside light is made incident from a surface sideon which a degree of a change in a refractive index in a vicinity of aboundary between the low-refractive index area and the high-refractiveindex area is relatively large, and is emitted from a surface side onwhich the degree of the change in the refractive index in the vicinityof the boundary between the low-refractive index area and thehigh-refractive index area is relatively small.

(2) The display device described in the paragraph (1),

in which the anisotropic scattering member is disposed in such a waythat the light is scattered when the outside light reflected within theimage display portion is transmitted through the anisotropic scatteringmember.

(3) The display device described in the paragraph (1),

in which the anisotropic scattering member is disposed in such a waythat the light is scattered when the outside light made incident from anoutside is transmitted through the anisotropic scattering member.

(4) The display device described in any one of the paragraphs (1) to(3),

in which the image display portion has a reflection type liquid crystaldisplay panel including a front substrate, a back substrate, and aliquid crystal material layer disposed between the front substrate andthe back substrate, and

the anisotropic scattering member is disposed on the front substrateside.

(5) The display device described in any one of the paragraphs (1) to(4),

in which the anisotropic scattering member includes plural scatteringmembers, different in scattering characteristics from one another,laminated one upon another.

It should be understood that various changes and modifications to thepresently preferred embodiments described herein will be apparent tothose skilled in the art. Such changes and modifications can be madewithout departing from the spirit and scope of the present subjectmatter and without diminishing its intended advantages. It is thereforeintended that such changes and modifications be covered by the appendedclaims.

The invention is claimed as follows:
 1. A display device comprising: areflection type image display portion including a sheet-like anisotropicscattering member, wherein in an area, in an in-plane direction, of theanisotropic scattering member, a low-refractive index area and ahigh-refractive index area are disposed in a mixture style, and whereinthe anisotropic scattering member is includes a first surface and asecond surface, the first surface having a relatively large degree ofchange in a refractive index in a vicinity of a boundary between thelow-refractive index area and the high-refractive index area, and thesecond surface having a relatively small degree of change in therefractive index in the vicinity of the boundary between thelow-refractive index area and the high-refractive index area.
 2. Thedisplay device according to claim 1, wherein the anisotropic scatteringmember is disposed in such a way that light is scattered when outsidelight reflected within the image display portion is transmitted throughthe anisotropic scattering member.
 3. The display device according toclaim 1, wherein the anisotropic scattering member is disposed in such away that light is scattered when outside light made incident from anoutside is transmitted through the anisotropic scattering member.
 4. Thedisplay device according to claim 1, wherein the image display portionhas a reflection type liquid crystal display panel including a frontsubstrate, a back substrate, and a liquid crystal material layerdisposed between the front substrate and the back substrate, and theanisotropic scattering member is disposed on the front substrate side.5. The display device according to claim 1, wherein the anisotropicscattering member includes plural scattering members, different inscattering characteristics from one another, laminated one upon another.